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R=<a href="%pathto:mser.vl_mser;">VL_MSER</a>(I) computes the Maximally Stable Extremal Regions (MSER)
[1] of image I with stability threshold DELTA. I is any array of
class UINT8. R is a vector of region seeds.
</p><p>
A (maximally stable) extremal region is just a connected component
of one of the level sets of the image I.  An extremal region can
be recovered from a seed X as the connected component of the level
set {Y: I(Y) &lt;= I(X)} which contains the pixel o index X.
</p><p>
The function supports images of arbitrary dimension D.
</p><p>
[R,F]=<a href="%pathto:mser.vl_mser;">VL_MSER</a>(...) also returns ellipsoids F fitted to the regions.
Each column of F describes an ellipsoid; F(1:D,i) is the center of
the elliposid and F(D:end,i) are the independent elements of the
co-variance matrix of the ellipsoid.
</p><p>
Ellipsoids are computed according to the same reference frame of I
seen as a matrix. This means that the first coordinate spans the
first dimension of I.
</p><p>
Notice that for 2-D images usually the opposite convention is used
(i.e. the first coordinate is the x-axis, which corresponds to the
column index). Thus, if the function <a href="%pathto:plotop.vl_plotframe;">VL_PLOTFRAME</a>() is used to plot
the ellipses, the frames F should be `transposed' as in F = F([2
1 5 4 3],:). <a href="%pathto:mser.vl_ertr;">VL_ERTR</a>() exists for this purpose.
</p><p>
<a href="%pathto:mser.vl_mser;">VL_MSER</a>(I,'Option'[,Value]...) accepts the following options
</p><dl><dt>
Delta
<span class="defaults">[5]</span></dt><dd><p>
Set the DELTA parameter of the VL_MSER algorithm. Roughly
speaking, the stability of a region is the relative variation
of the region area when the intensity is changed of +/-
Delta/2.
</p></dd><dt>
MaxArea
<span class="defaults">[0.75]</span></dt><dd><p>
Set the maximum area (volume) of the regions relative to
the image domain area (volume).
</p></dd><dt>
MinArea
<span class="defaults">[3 / numPixels]</span></dt><dd><p>
Set the minimum area (volume) of the regions relative to
the image domain area (volume).
</p></dd><dt>
MaxVariation
<span class="defaults">[0.25]</span></dt><dd><p>
Set the maximum variation (absolute stability score) of the
regions.
</p></dd><dt>
MinDiversity
<span class="defaults">[0.2]</span></dt><dd><p>
Set the minimum diversity of the region. When the relative
area variation of two nested regions is below this threshold,
then only the most stable one is selected.
</p></dd><dt>
BrightOnDark
<span class="defaults">[1]</span></dt><dd><p>
Detect bright-on-dark MSERs. This corresponds to MSERs of the
inverted image.
</p></dd><dt>
DarkOnBright
<span class="defaults">[1]</span></dt><dd><p>
Detect dark-on-bright MSERs. This corresponds to MSERs of the
original image.
</p></dd><dt>
Verbose
</dt><dd><p>
Be verbose.
</p></dd><dt>
REFERENCES
</dt><dd><p>
[1] J. Matas, O. Chum, M. Urban, and T. Pajdla, &quot;Robust wide
baseline stereo from maximally stable extremal regions,&quot; in
Proc. BMVC, 2002.
</p></dd></dl><p>
See also: <a href="%pathto:vl_help;">VL_HELP</a>().
</p></div></group>
